This invention relates to a hinge assembly suited to be used for turnably connecting two articles together such as a keyboard and a liquid crystal display of a notebook-type personal computer.
In general, a hinge assembly used for a notebook-type personal computer includes one pair of hinge members which are fixed to a keyboard and a display, respectively. One hinge member has a support hole and the other has a shaft part. The shaft part is turnably inserted into the support hole, thereby turnably connecting the pair of hinge members together and therefore, turnably connecting the keyboard and the display together. The shaft part is press-fitted into the support hole. By this, a frictional resistance is generated between the outer peripheral surface of the shaft part and the inner peripheral surface of the support hole. The frictional resistance thus generated makes it possible to maintain the display in an optional turning position.
The frictional resistance between the shaft part and the support hole is set to a comparatively large value in order to stop the display in an optional position overcoming the turning force caused by the dead weight of the display. However, if the frictional resistance is increased, there occurs a problem in that it becomes difficult to turn the display because the display must be turned with a force large enough to cope with the frictional resistance. Moreover, if the frictional resistance is large, there occurs another problem in that the keyboard tends to turn together with the display when the folded display is opened. In order to turn only the display, it is necessary to keep pressing the keyboard. This makes it practically impossible for the user to open the display with one hand.
It is a first object of the present invention to provide a hinge assembly through which two articles such as a keyboard and a display of a personal computer can be turned lightly.
In order to achieve the first object, a first form of the present invention provides a hinge assembly comprising a first hinge member having a support hole, a second hinge member having a shaft part and turnably connected to the first hinge member by the shaft part being turnably inserted into the support hole, and biasing means disposed between the first hinge member and the second hinge member, the shaft part being press-fitted into the support hole so that frictional resistance is generated between an outer peripheral surface of the shaft part and an inner peripheral surface of the support hole, the biasing means biasing the first and second hinge members towards a neutral position side when the first and second hinge members are turned in normal and reverse directions from the neutral position.
In this first form, it is preferred that a receiving hole is formed in the shaft part such that the receiving hole extends from a front end face of the shaft part towards the inside, and the biasing means is received in the receiving hole. It is also preferred that a coiled spring is used as the biasing means. It is also preferred that the first hinge member is formed with a first and a second engagement portions, and the second hinge member is formed with a third and a fourth engagement portions, so that when the first and second hinge members are turned in one direction from the neutral position, the first and fourth engagement portions are engaged, respectively, with a first and a second end part of the coiled spring to twist the coiled spring in accordance with turning motion of the first and second hinge members and the second and third engagement portions are brought away, respectively, from the second and first end parts of the coiled spring, and when the first and second hinge members are turned in the other direction from the neutral position, the first and fourth engagement portions are brought away, respectively, from the first and second end parts of the coiled spring and the second and third engagement portions are engaged, respectively, with the second and first end parts of the coiled spring to twist the coiled spring in accordance with turning motion of the first and second hinge members.
In order to achieve the above object, a second form of the present invention provides a hinge assembly in which one (first article) of two articles is turnably connected with a lower end part of the other article (second article) about a generally horizontal rotation axis such that the second article can turn normally and reversely downward from an upright position where the second article are erected vertically, the hinge assembly comprising a pair of first and second hinge members fixed to the first and second articles, respectively, the first hinge member being formed with a support hole whose axis is aligned with the rotation axis and the second hinge member being formed with a shaft part which can turnably be inserted into the support hole, the shaft part being press-fitted into the support hole so that frictional resistance is generated between an outer peripheral surface of the shaft part and an inner peripheral surface of the support hole, biasing means being disposed between the pair of first and second hinge members, the biasing means being adapted to bias the second article, which has been turned downward from the upright position, towards the upright position side through a hinge member fixed to the second article, a following relation being established among various turning forces acting on the second article,
|Fsxe2x88x92Fg| less than Ff 
where Fg represents a force caused by a dead weight of the second article, Fs, a force caused by a biasing force from the biasing means and Ff, a turning force corresponding to the frictional resistance, respectively.
In this second form of the present invention, it is preferred that a receiving hole is formed in the shaft part such that the receiving hole extends from a front end face of the shaft part towards the inside, and the biasing means is received in the receiving hole. It is also preferred that a coiled spring is used as the biasing means. It is also preferred that the first hinge member is formed with a first and a second engagement portions, and the second hinge member is formed with a third and a fourth engagement portions, so that when the second article is turned in one direction from the upright position, the first and fourth engagement portions are engaged, respectively, with a first and a second end part of the coiled spring to twist the coiled spring in accordance with turning motion of the second article and the second and third engagement portions are brought away, respectively, from the second and first end parts of the coiled spring, and when the second article is turned in the other direction from the upright position, the first and fourth engagement portions are brought away, respectively, from the first and second end parts of the coiled spring and the second and third engagement portions are engaged, respectively, with the second and first end parts of the coiled spring to twist the coiled spring in accordance with turning motion of the second article.
A second object of the present invention is to provide a hinge assembly, in which in the case where a pair of hinge members are biased by a coiled spring, the coiled spring is twisted in the same direction irrespective of the turning direction of the pair of hinge members.
In order to achieve the second object, a third form of the present invention provides a hinge assembly comprising a pair of hinge members turnably connected together for turning in normal and reverse directions from a neutral position and a coiled spring for biasing the pair of hinge members, which have been turned in normal and reverse directions from the neutral position, towards the neutral position side, the first hinge member of the pair of hinge members being formed with a first and a second engagement portion and the second hinge member being formed with a third and a fourth engagement portion, so that when the pair of hinge members are turned in one direction from the neutral position, the first and fourth engagement portions are engaged, respectively, with a first and a second end part of the coiled spring to twist the coiled spring in accordance with turning motion of the pair of hinge members and the second and third engagement portions are brought away, respectively, from the second and first end parts of the coiled spring, and when the pair of hinge members are turned in the other direction from the neutral position, the first and fourth engagement portions are brought away, respectively, from the first and second end parts of the coiled spring and the second and third engagement portions are engaged, respectively, with the second and first end parts of the coiled spring to twist the coiled spring in accordance with turning motion of the pair of hinge members.
In this third form, it is preferred that the coiled spring is twisted in a winding direction. It is also preferred that the first hinge member is formed with a support hole extending on a rotation axis thereof, the second hinge member is formed with a shaft part turnably inserted into the support hole, the shaft part is formed with a receiving hole extending from a front end face of the shaft part towards the inside, and the coiled spring is received in the receiving hole. In this case, it is preferred that the support hole is in the form of a through-hole whose opposite ends are open, the shaft part is inserted all the way through the support hole, opposite end parts of the coiled spring are projected outward from the opposite end parts of the support hole and also projected from an outer peripheral surface of the shaft part, the first and second engagement portions are formed on opposite end faces of the first hinge member which is formed with the support hole whose opposite end parts are open, and the opposite end parts of the shaft part projecting from the support hole is formed with the third and fourth engagement portions, respectively.